Feared on the brink of being wiped out a decade ago by invasive Asian shore crabs, the native mud crabs are once again kings of their muddy domains.

DE-LA-WARE! DE-LA-WARE!! DE-LA-WARE!!!

The chants of victory echo across Delaware Bay as the invaders crawl away.

Charles Epifanio, a scientist in the University of Delaware's College of Earth, Ocean, and Environment was shocked at the sea change.

Epifanio started researching Asian shore crabs with support from Delaware Sea Grant a few years after they first appeared in Delaware Bay in 1988.

"When this crab arrived here and took over the rocky intertidal habitat, it was remarkable," Epifanio said. "It wasn't gradual. It exploded."

By 2001, Asian shore crabs had all but replaced two of the three native species of mud crabs. Researchers assumed the trend would continue and did not resume counts until a follow-up project by a summer intern in 2011 to see whether there were any changes.

The resurgence of the native crab found by the intern so shocked Epifanio – "At first, I thought she had it wrong," Epifanio said – that he went back out with the student to check her technique.

Epifanio and a graduate student then repeated the experiments in 2012 and 2013 and found the same thing.

The invasive Asian shore crabs, which in 2001 had made up 75 percent of the crabs found in rocky habitat near the mouth of Delaware Bay, now made up just 25 percent.